Reginald Innes Pocock

“ Metasoma.—This region of the body in the Scotch specimen closely resembles that of the Swedish specimen, the same surface, namely the ventral, being in each case uppermost. Peach, however, states that the dorsal surface of the posterior caudal segments is in part exposed. According to my interpretation, on the contrary, in all the segments it is the area lying between the inferior lateral keel on the left side (inf. lat. and sup. lat., Pl. 19) and the superior lateral keel on the right that is exposed. ”

“ At the extremity of the sixth segment in the scorpion's leg, or rather on the arthrodial membrane between it and the seventh, there are either one or two "pedal" spurs, which represent, I suggest, the lobate sclerites in the same position on the leg of Limulus. ”

“ In Palæophonus the sternal plate of the prosoma lies apparently behind the basal segments of the fourth legs as in Limulus, and, as in the latter and in the Eurypterida, the basal segments of all the appendages were in contact or capable of meeting in the middle line. On the other hand, the coxæ of the fourth were small and functionless so far as the mouth was concerned, and food was probably crushed by those of the chelæ as in recent scorpions, the sterno-coxal sclerites of the second and third pairs assisting in this process, and preventing the escape of nutritive juices. ”

“ The fingers are thinner, more taper, and straighter than in the Gotland specimen and recent scorpions. No distinct joint between the finger and hand is discernible, although presumably it is the under side of the hand and of the moveable finger that is exposed to view, both on the right and left sides. ”

“ According to Thorell this specimen exhibits on its right side a portion of a displaced sternal plate, upon which a distinct stigma is visible. This sternal plate he assigns to the third somite of the mesosoma; but a glance at his drawing shows that the greater part of it lies at the sides of and beneath the tergite of the second somite, and that at all events a large part of the third sternite is situated on the left-hand side beneath its corresponding tergite. ”

“ No genuine stigmata were discovered, but on some of the mesosomatic somites a curved ridge running obliquely outwards and backwards on the sides of the segments was traceable. The ridge on the second somite Laurie interprets as the impression of the outline of the pecten, those on the others as the outline of a plate-like gill-bearing appendage. ”

“ The figure gives a magnified view of the specimen of Palæophonus Hunteri, Pocock, from the Upper Silurian of Lesmahago, Lanarkshire, It. was formerly in the collection of Dr. Hunter, and is now in the Kilmarnock Museum. This lithograph was executed from the specimen itself by Miss G. M. Woodward, under the supervision of Mr. R. I. Pocock, in October, 1900.
I—VI. Prosomatic appendages. st. Sternal area of prosoma. gen. Genital cleff. pect. Pecten, or external branch of appendage of second somite of mesosoma. end. internal branch of appendage of second somite of mesosoma. sup. lat., inf. ”

“ Both of these keels are granular. As in most recent scorpions, a pair of median keels (inf. med., Pl. 19) lie along the lower surface of the tail, between the inferior lateral keels on the first four segments of the tail. ”